Pregnancy with Anti-MuSK-Positive Myasthenia Gravis That Was Diagnosed During Pregnancy A Case Report

BACKGROUND: Anti-muscle-specific tyrosine kinase (MuSK)-positive myasthenia gravis (MG) has a late onset in the 4th decade of life and a poor response to medical treatment. Few cases of pregnancy with anti-MuSK-positive MG have been described. We report a case of pregnancy with anti-MuSK-positive MG that was diagnosed during pregnancy. CASE: A 46-year-old healthy primiparous woman was referred to Okayama University Hospital at 23 weeks' gestation because of antiMuSK-positive MG that was diagnosed during pregnancy in the first trimester. Emergent cesarean section was performed at 30 weeks' gestation because of severe preeclampsia and pre-crisis of MG. She received medication and plasmapheresis for hypertension and severe MG symptoms and was discharged on day 35 after delivery. The neonate had no symptoms of transient neonatal MG, and anti-MuSK antibody was positive at birth and then decreased to the normal range at 5 months old. CONCLUSION: Our case and previous reports indicate that pregnancy with anti-MuSK-positive MG might have the same or a relatively higher risk for the mother and neonate as compared with anti-AChR-positive MG. Multidisciplinary management throughout the perinatal period should be provided for pregnancy with anti-MuSK-positive MG.